Aquaculture is currently the fastest growing sector in food production around the world. Waste discharge is a key hurdle to the growth of the aquaculture industry and the adaptation of new production facilities. The development of an apparatus that allows for the safe, internal processing of solid waste within a recirculating aquaculture system allows for the controlled production of various aquatic species without concern of accidental release of specimens or harmful waste products, opening the door for aquaculture development across the globe.
Waste water from aquaculture generally contains high levels of suspended solid wastes and ammonia. Solid wastes degrade into ammonia under anoxic conditions, and they can use up much of the dissolved oxygen in the water when degrading under aerobic conditions. Both high levels of ammonia, regardless of dissolved oxygen level of the water, and low levels of dissolved oxygen are harmful to the aquatic species and plants being cultivated.
Prior systems for solid waste management require solid waste, and associated water, to be separated with solids collected and removed from the system, resulting in an increased loss of water, loss of nutrients in the solid waste, as well as a discharge of ammonia waste into local environments, which can be harmful to local biota. One current system employs a multi-valve, 4-tank system and uses a vertical bead filter commonly found on swimming pools. This system, however, requires significant training and is energy intensive. Additionally, these systems are not truly zero-discharge, as the system requires that excess solid waste build-up be removed from the system periodically.
In addition, Dr. James Rakocy, one of the leading experts in aquaponic system design, in 2012, in the book Aquaculture Production Systems, by Tidwell, pp 344-386, delivered a paper titled, Aquaponic-Integrating Fish and Plant Culture. In this paper, Dr. Rakocy noted the difficulties of using media beds in commercial aquaponic systems, specifically pointing out that these beds are prone to clogging, the formation of anaerobic zones, and potentially producing methane and hydrogen sulfide, which are highly toxic to fish.
Furthermore, Leonard and Lennard, in their paper, A comparison of three different hydroponic subsystems: gravel bed, floating and nutrient film techniques, in an aquaponic test system, in Aquaculture International, Vol 14, Issue 6, pp. 539-550, note the problems with utilizing media beds in an aquaponic system, citing the need to clean system media, and flush excess accumulated solid waste from the beds.
Therefore, there exists a need to provide an aquaponics system that removes harmful ammonia, maintains high levels of dissolved oxygen internally, and prevents accumulating solid waste from the beds, without discharging solid waste from the system.